The cost of replacing tires in a commercial vehicle is the second largest expense, in some estimates representing 11% of the total vehicle operating costs. Only fuel costs (ranging between 28%-37% of the total vehicle operating costs) outpace the cost of replacing the tires. Improper maintenance of tire pressure may result in significantly higher fuel costs and lowered tire life. For example, under-inflated tires can lower gas mileage by 0.3% for every 1 psi drop in pressure. Such rising costs may be significant for fleet operators managing hundreds or thousands of commercial vehicles.
On-board automatic inflation systems are currently available for use on trucks and other vehicles in an attempt to address aspects of the above problem. Such systems automatically deliver make-up air to a vehicle tire in the event that the tire is punctured or begins to leak for other reasons. For a given trailer, truck, or other vehicle axle assembly, automatic tire inflation systems can be installed for monitoring and maintaining a desired air pressure in each tire individually. However, conventional automatic tire inflation systems pressurize the tire to a predetermined and fixed pressure. For example, in current systems, the automatic tire inflation system can be configured to maintain a tire pressure of 95 pounds per square inch (psi). Accordingly, as the tire begins to leak air (e.g., either because of being punctured or other conditions), the conventional automatic tire inflation system will adjust the tire pressure back to 95 psi. However, pressurizing the tire to a predetermined or fixed pressure may not be ideal for all conditions.
Additionally, because the automatic inflation systems continuously provide air to a tire when the air pressure of the tire falls below the predetermined or fixed value, the driver or fleet operator may continue to operate the vehicle with the tire has been structurally compromised (e.g., punctured). In such cases, irreparable damage may occur to the tire or the vehicle (e.g., a tire blowout during operation may result in accident that may be fatal).
Thus, improvements in automatic inflation systems are desired.